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| Titel |
Late-Holocene climate and ocean variability from tree-rings and high-resolution marine archives in North Norway |
| VerfasserIn |
A. J. Kirchhefer, W. Ambrose, M. Carroll, M. Hald, S. Helama, K. Husum, B. R. Schöne |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250024702
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| Zusammenfassung |
| Tree-rings of Scots pine, Pinus sylvestris L., at the arctic-alpine tree-line in North Norway
provide information on summer air temperatures for the past 1500 years. When accounting
for tree-ring autocorrelation, July temperatures explain up to 75 % of the main
regional growth variability 1895-1992 extracted from 16 site chronologies between the
Vesterålen Archipelago and the inland peneplain of Finnmarksvidda. The longest
individual chronologies provide reconstructed July temperatures since AD 1100 and
500 for the coast (Forfjorddalen, Radj2 - 40 %) and the intra-alpine valleys
(Dividalen, Radj2 - 30 %), respectively. However, the response patterns vary in
space and time: The coastal chronologies reflect a longer period affecting cambial
activity, i.e. (May-) July-August. In the mid 20th century, with certain differences
between coast and inland, a change occurred towards earlier, positive temperature
responses, with June replacing August and March replacing April. Simultaneously, the
negative effect of July precipitation faded out. Apparently, this is a response to
changes in the atmospheric circulation pattern as described by the Arctic Oscillation
AO.
The coastal mean pine chronology correlates reasonably well with July-August sea
surface temperatures (SST) of the entire North-Norwegian coast (r = 0.4, HadlSST1
1870-1994). Together with first results from shell growth increments (SGI) of Arctica
islandica L., this opens for future multiproxy reconstructions of coastal SSTs. SGIs of young
shells from the northern shore of the Vestfjorden contain a signal of mean air temperatures (r
= 0.66, 1976-2004), and four specimens collected near Tromsø cross-date with
local pine chronologies (r = 0.50, 1806-1868). Furthermore, high-resolution marine
sediments of the Malangen fjord and Andfjorden allow comparisons of tree-ring derived
summer temperatures with bottom water temperatures (BWT) derived from δ18O of
benthic foraminiferae. Challenges faced when integrating terrestrial and marine
climate proxies are related to differences in time scales and dating accuracy as well as
in the time windows and climate parameters captured by the respective archives. |
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